This invention relates to an improved safety ski binding for detachably holding a ski boot on a ski, and more particularly to a binding which discriminates in operation between forces applied to the lateral outside edge of a ski, and forces applied to the lateral inner edge of the ski. Still more particularly, the invention relates to a ski binding of the plate type which is self-restoring after release and which offers improved retention of the ski to the boot under certain commonly encountered skiing conditions which have heretofore tended to cause unwanted release of the bindings, while retaining a high or significant safety margin under conditions which present a risk of serious injury to the skier.
It is conventional in the sport of snow skiing to use a safety binding for attaching the boot of the skier to the top surface of the ski. The binding is generally intended to prevent serious injury to the skier by releasing the boot from the ski when the forces applied to the ski are of such a nature or magnitude as to cause a dangerous torque or other force to be applied to the skier's leg. Although the use of such safety bindings has reduced the incidence of serious injuries to skiers, many skiers continue to be injured even while wearing such safety bindings, because of deficiencies inherent in the design or the operation of the binding under commonly encountered skiing conditions.
In safety ski bindings heretofore known, it has generally been considered desirable to provide a mechanism which releases when a lateral force of a defined magnitude (adjustable by the skier) is applied to the binding, regardless of the side (i.e., inner or outer) of the ski to which the force is applied. Such bindings are generally symmetrical in their operation about the longitudinal axis of the ski, so that if a force of a given magnitude applied transversely to the side of a ski at a given location along its length causes the binding mechanism to release, the same force applied in the opposite direction to the corresponding location on the opposite side of the ski will also cause the binding to release. Further, in some bindings the same mode of release is used at the toe and the heel portions of the boot, making the operation of the binding symmetrical about a transverse axis through the boot, i.e., if a transverse force applied to the ski at a given distance forward of the boot will cause the binding to release, the same force at the corresponding distance rearward of the boot will also cause the binding to release, regardless of whether the force is applied to the inside edge or the outside edge of the ski.
While it was originally believed that a safety ski binding providing the greatest possible number of modes of release, e.g., lateral release, both inwardly and outwardly at the heel and toe of the boot, roll release at both heel and toe, vertical release at heel and toe, and thrust release at heel and toe, would provide the greatest protection for the skier, this has not proved to be true in actuality. During many skiing maneuvers, particularly by an advanced or expert skier, there are at times produced substantial lateral forces on the ski, which forces are nevertheless well within the safety margin necessary for the protection of the skier and entirely within his control. Under such circumstances, some of the prior art bindings have a tendency to release unexpectedly, since the force tending to separate the boot and the ski exceeds the force necessary for releasing the binding, even though there is no imminent danger to the skier. The unexpected release of the bindings in this manner can cause the skier to fall and thus suffer injuries which the bindings are intended to prevent. Moreover, the tendency of a skier who experiences an unexpected release during a controlled maneuver is to tighten the release setting of his bindings so as to avoid a recurrence. Tightening the bindings, however, reduces the margin of safety which the bindings were intended to provide when a dangerous situation exists.
For example, a binding providing both inward and outward lateral release at both toe and heel will release, as it should, if the skier catches a tip of his skis in an obstruction, causing a large twisting movement or torque to be applied to his leg. This type of binding, however, may also release unexpectedly during a controlled maneuver, such as a sideslip, which imparts a transverse force to both the toe and the heel on the same side of the boot and thus produces little or no torque or other dangerous force. If a binding of this type, however, is tightened sufficiently to prevent such an unexpected and unwanted release, it may fail to operate reliably when necessary to protect the skier in a truly dangerous situation.